1. Field of the Invention
The present invention relates to a lithium secondary battery, and more specifically, to a lithium secondary battery with excellent low temperature properties.
2. Description of the Related Art
With rapid progress of electronic, telecommunication and computer industries, portable electronic communication devices such as a camcorder, mobile phone, notebook PC, etc. have been remarkably developed. Accordingly, the demand for a lithium secondary battery as a power source capable of driving the above device is also increased. In particular, with regard to applications of eco-friendly power sources such as an electric car, uninterruptible power supply, electromotive tool and satellite, research and development have been actively proceeded in domestic field and other countries such as Japan, Europe, United States, etc.
Among currently used secondary batteries, the lithium secondary battery developed since early 1990's includes an anode made of a carbon material capable of absorbing and desorbing lithium ions, a cathode made of lithium-containing oxide, and a non-aqueous electrolyte containing lithium salt dissolved in a mixed organic solvent in a suitable amount.
In this regard, as the application of the lithium secondary battery is more enlarged, it is often used as a power source of an electrical vehicle, or the like. In such a case, it is necessary for the lithium secondary battery used in the electrical vehicle to exhibit a performance capable of being operated under severer environments such as hot or low temperature environments than the mobile phone, notebook PC, etc. The vehicle should be operated at a low temperature such as winter, and therefore typically, excellent charge/discharge performances, and output properties at a low temperature may be required in the lithium secondary battery.
However, the power and charge/discharge performances are severely reduced under a low temperature due to a decrease in an electrochemical reaction rate, such that the demand for a lithium secondary battery having excellent low temperature properties has been increased.
Korean Patent Laid-Open Publication No. 2004-11851.7 discloses a non-aqueous electrolyte additive for a lithium secondary battery.